Dental impression tray



June 3, 1952 w. A. MAY

DENTAL IMPRESSION TRAY Filed May 18, 1950 ATTGRNEYS.

Patented June 3, 1952 OFFICE DENTAL IMPRESSION TRAY William A. May, Philadelphia, Pa. Application May 18, 1950, Serial No. 162,670

1 Claim.

The present invention relatesv to dentists irnpression trays of the character employed in crown and bridge work for making impressions of dental surfaces.

A purpose of the invention is to avoid the labor previously involved in reassembling the broken fragments of a crown or bridge impression molding in order to obtain the correct contour of the dental surfaces.

A further purpose is to permit breaking of the plastic molding along the line of the teeth and to secure adherence of the broken fragments to the crown or bridge tray while the broken fragments are deformed or manipulated in removing the molding and tray from the mouth of the patient.

A further purpose is to hinge the corners of the channel cross section of the crown and bridge tray by employing a foldline in cardboard and the like.

A further purpose is to make a crown or bridge tray with a backing of pliable sheet material such as cardboard folded into a channel cross section having open ends and lined with an open mesh fabric secured to the backing and providing for firm adherence of the plastic molding to the backing.

Further purposes appear in the specification and in the claim.

In the drawings I have chosen to illustrate a few only of the numerous embodiments in which myinvention may appear, selecting the forms shown from the standpoint of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure l is a perspective of the improved crown and bridge tray of the invention. I v t Figure 2 is a section on the line 2-2 of Fig-.- ure 1.

Figure 3 is a perspective showing the crown and bridge tray with a charge of plastic molding material inserted.

Figures 4 to 7 are sections similar to Figure 2, omitting the stitching, showing'the steps in making an impression.

Figure 8 is a top plan view of the completed impression of Figure 7.

Figure 9 is a section similar to Figure 2 showing a variation in the tray of the invention.

In the drawings like numerals refer to like parts throughout.

At 'the present time crown and bridge trays are usually made of metal. A mass of plastic material such as a plaster of the character of plaster of Paris is placed in the tray and the 2 H tray and charge of plaster are inserted in the mouth of the user. After the plaster sets it is necessary for the dentist to break apart the pieces ,of the impression in order to remove the nowhardened plastic molding from around the teeth and gums. In the end the dentist obtains several different separate fragments of the solidified impression, and these fragments constitute .in effect a jig-saw puzzle. which must be solved in order to assemble the parts in the proper relation prior to using the impression for manu-- facturing of a denture such as a crown or bridge.

The separated fragments of the solidfied plastic material do not remain adhering to the crown and bridge tray of the prior art but separate therefrom and there is always the possibility that fragments will not only become misplaced in their relation to one another but will actually be lost or swallowed in the process of removal. "In the above discussion it must be carefully kept in mind that the procedure under discussion of obtaining a crown and bridge impression is entirely different from that of obtaining a bite impression, in which latter case wax is ordinarily used in a bite tray of obtain an impression of the mating surfaces of a set of teeth, usually including artificial dentures. In the case of a bit tray the problem of separation of a plastic molding material and reassembly of compo nents does not exist.

In accordance with the invention I make a crown and bridge tray of a flexible backing preferably cardboard with open ends and desirably of channel shape, desirably capable of hinging at the corners of the channel, and lined with an open mesh fabric adhering to the backing. By this procedure the flexible backing can be used to manipulate the plastic material including the pieces thereof, while the pieces of plastic are held in their proper relation to one another and to the backing by the fabric lining of the backing. In this way the tray can be manipulated as a unit to break the plastic material into fragments, to hold thefragments together in their proper relation and then to reassemble the fragments.

Asshown in Figures 1 and 2, the crown and bridge tray of the invention comprises-a backing20 of any suitable sheet flexible material such as cardboard, straw board or the like having a channel of U-shaped.cross section forming sides or arms 2| and 22 and a bottom 23 intercon- The cardboard is flexible enough so that it can readily be hinged at the front lines under the action of the fingers and can also readily be formed at any other portion of the sheet. The ends are open as shown. 'It is preferable to curve the corners as illustrated.

.Extending over the interior surface of the backing is a lining 26 suitably of an open mesh fabric such as cotton gauze, or netting. The lining is preferably stiffened as by sizing suchas starch or sugar that will make the lining lie flat.

It is important that the lining provides sufficient space between the lining and the backing so that the plastic material forming the impresbled in Figures 7 and 8; It is therefore no longer "necessary for the dentist to reassemble a jig-saw sion can be embedded into the mesh of the lining.

and into the space between the lining and, the I,

. backing. V

the lining to the backing suitably bystitch lines Any other suitable means of V This is best accomplished by sewing 21, 23, 30 and 3|. attachment which leaves the mesh of the fabric open may be employed. v

--Figures 3 to 8 show the preferred mannerof "forming an irnp'ressi'cn usingthe'riewv crowniand bridge tray. 7 I

*As shown in'Fignre 3 a plastic massiz such as plaster of Paris or any other 'dental impressi'on plaster, suitablyfiavored and perfumed, is placed in" the interiorof the tray. ii-"he tray is therr applied inf-position to bring the-plastic mass :32 an-round and against the-teeth EB-and gums 3-4.

In making an impression of upperteeth the tray will be upright, but for-lower teeth the tray will be inverted as shown in Figure 4.; The operator Will press the tray toward the teeth'to shapethe molding to the teeth and gums. Once the impression has'been properlyformed, as shown in Figure 4, usingpressure of theifingers to'cause' the plastic molding material to conform' to the contour of the teeth-and gums, the plastic ;mater'ial'will alsobe'thoroughly intrudedinto the interstices of the 'openmeshfabric lining so 'that a good bond willbe obtained between the plastic materialand the lin ing. The plastic-materialfl in Figure 4 is allowed to set and thence is broken suitably along'the line oflongitudinal-least resistance or weakest point, which usually is "along the line of centers of the-teeth= at' 35." The pressure applied for-breakage can be applied to the sides of thetray with the fingersbrwi-t'h a dental tool, and the broken pieces- 36- and 3! of the now-solidified plastic material remain in their proper place due to their intimate bonding 'Withthe' fabric lining. The backing tends to bend or fold at 38 along the lineof 'the break,

permitting rocking separation of the portion 't'fi and 3-1 for the purpose ofremoving thesolidified plastic material from the teeth by furtherseparation 'of the parts as shown in "Figure 6. I

After the trayandthe broken-pieces iSfi and 31 "of the" plastic material are --removed from the mouth, the components oan-be reassembled by bending back thesides 12 l and 22 toward onc'ane other until the structure assumes the same relapression o'f the lingual surface42 and an impression of the labial or buc'calsurface 43. Y

"puzzle, as the broken parts of the plastic material remain in their correct relationship even thoughthe tray must be held in inverted position and even tho-ugh more than one break line must be used in removing the tray from the mouth. 1 The folding action along the break line due to the flexibility of the cardboard and due to. the hinge lines. at the corners of the channels,

which are particul'arly guseful inapplyinglateral pressure "before the plastic material sets, permit the dentist to separate the parts Wider'an-d stiH bring them together in thecorrect relationship. In some-cases it maybe desirable to accentuate the fold linesiati the corners of the channel and this has. been done in Figure 9 by: areverse-bend fold at 24' at each corner. V

It will be understoodof course that the cardboard: lining, thread and other' materials "used should be of adequate purity 1for -i-nsertion-mto the mouth, and should be properly sterilized; and the cardboardparticularly should-be of a high enough wet strength to stand sterilizing and use in the mouth Without danger of losing-its shape. In view of my invention and-.disclost-trfiafiations and modifications to meet individual fwhim or particular'ne-ed will doub tless become evident to others skilled in the art, to obtain allo-r' part of the benefits ofmy-structuregand process shown,

and I, therefore, claim .allrsueh insofar-as they fall .within'the reasonable spirit'and scope of my claim. 1

. Having th us described my i-nvention what I claim as new and: desire to secure by Letters Pat entis: I

In a dental impression tray, a cardboard channel having a base and arms extending from the sides of thebase and connected-to the-baseby hinge lines, a liner of open meshfabricextend'ing over the inside of the 'baseand arms,'an dstitch ing uniting the liner to the channel, whereby-aft: er making an impression in the tray, a'parting line for th-eimpression can be-broken by'ma n'ip ulating the arms of the'tray, but the impression material is held -to'the channel by thefabrioiand stitching, and the impression ones out of the mouth can be reassembled by again manipulating the arms of the'tray.

WILLIAM .AJ'MAY. i

' REFERENCES CIT-ED The following references are of reCordinthe file of this patent:

UNITED STATES PATENTS Kalv-in -1 Aug; 20, 1 935 

